Microphone mounting



E. C. WOOD.

MICROPHONE MOUNTING.

APPLICATLON FILED APH,25,19'18.

Patented June i3, i922.

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UNTTED STATES PATENT DFFTQL@ EDWARD C. WOOD, OF SOMERVLLE,MASSACHUSETTS, ASSIGNOR TO SUBMASRINE SIGNAL COMPANY, 0F BOSTON,MIASSACHUSETTS, A CORPORATION OF MAINE.

MICROPHONE MOUNTING.

Application lcd April 25, 191e.

T o fr?? :clio/n if 'may concern:

Be it known that I, EDWARD C. lvooo, of Somerville. in the county ofMiddlesex and State ot Massachusetts, a citizen of the Vnited States.have invented a new and uset'ul Improvement in Microphone Mountings, ot'which the t'ollowing is a specification.

My invention relates especially to the mounting ot' a microphone upon atuned diaphragm such that external pressure will not change the pitch ofthe diaphragm. My invention is more particularly adapted for cases inwhich it is necessary or desirable to hang the microphone overboard froma vessel or pier.

A microphone when used as a submarine receiver is usually mounted on ametallic diaphragm which preferably is tuned to receive vibrations ot agiven pitch, more or less to the exclusion of other sounds. When mountedin a casing of such a character as not to interfere with its receptionof sound waves t'rom the surrounding water, upon submerging thisdiaphragm it is submitted to a pressure due to its depth of submersion,which interferes more or less with the pitch to which it is tuned. Thepurpose ot my invention is to provide means such thatthe diaphragm willmaintain tits normal pitch however deep it may be submerged, thepressure on both sides ot' the diaphragm being automatically equalized,so that the device asy a whole may bc self-equalizing.

My invention will be understood by reference to the drawings in which itis shown in its preferred form.

Figure 1 is a front elevation,

Fig. 2 is a vertical section, and

Fig. 3 is a side elevation of a device in which my invention isembodied.

A is a circular casing having a chamber a at its centre and an openingL1 opposite said chamber closed by a screw plug a2. Opposite the"opening(1,1 is a second opening a3. The front tace of the casing has twocircular projections thereon, one forming a rim B to which is attachedby screws a diaphragmholding ring C, the other B1 being a bridge Y overwhich the diaphragm D is stretched. The diaphragm D is provided withopenings near its edge tor the screws 7) and its outer edge ispreferably turned outwardly and is clamped against the eriphery of thering C Iby a hoop c which. may be soldered or driven into place toprevent the diaphragm Specification of Letters Patent. Patent-@d Jun@113, 1922,

Serial No. 230,799.

t'rom yielding under the strain set up by the ring E.

The diaphragm D is timed by means of the ring E which screws into thering C.

The ring E is provided with Spanner holes e to screw it into place.

It will be noted that the tuning ring E is larger in diameter than thebridge B1 and smaller in diameter than the holding ring C so that byscrewing it against the diaphragm it will strain the diaphragm over thebridge B1 and thus make it responsive to any desired pitch. These partsall form a water* tight chamber t0 one side of the casing, whichotherwise would be open.

Upon the diaphragm D is mounted the microphone G by means of a stem g'in the usual way, the microphone being in the chamber a and its stem gpassing outwardly through the opening a3. A `neck H at the top edge ot'the casing has a stuffing box of ordinary construction (not shown)through which pass out the microphone leads d, d, which pass from thecasing and preferably through a rubber tube a4 located therein to centreand protect them.

From the chamber a projects downward a passage K having a test opening7i: closed by a plug This passage K is connected with acollapsiblemember K1 by a watertight coupling which as shown comprises ashort metallic pipe L threaded to sc rew into the casing and enlarged atits outer end and properly shaped to have drawn over it the open end ot'the collapsible member K1. The coupling proper comprises a clampingsleeve L1 and nut L2.

As shown the collapsible member K1 comprises a rubber tube the lower endof which is sealed to make it both watertight and airtight, and all thejoints of the device are made watertight and airtight so that the deviceis practically sealed, and under these circumstances of course thecollapsing in any way of the collapsible member K1 will result in thecompression ot the air contents of the device.

in practice, when this device is hung overboard in the water thecollapsible member K1 will bc collapsed by water pressure, but thepressure on the collapsible member K1 will compress the air inside thedevice and, being the same as the pressure on the diaphragm D, the twowill equalize each other it the parts are properly proportioned sowhichy ring sald diaphragm that the'device may be consideredself-equalizing in every respect, the pressure on the two sides of. thediaphragm being at all times equal. Thus the pitch of the diaphragm Willin no Wise be changed, nor Will it lose its effectiveness because of anyunequal pressure upon its tWo sides.

I 'do not mean to limit myself to the precise form of my invention shownas other forms thereof Will occur to those skilled in the art.V Y The,collapsible member vshown may be dierently shaped and constructed andinsteadof air other gas may be used if desired. Moreover, as a pressureneutral# izer my method is equally efective Whether used With a tuned oruntuned diaphragm.

What I claim as my invention is 1. A microphone instrument, forsubmarine use, comprisin body casing parts Within which is a cham er, acircular bridge` on one of said body parts, a diaphragm so mounted as toform one side of Said chambei` and render the same Water-tight, amicrophone mounted at one side of'said diai phragm in said chamber, ahollow collapsible member serving as an air container and the chamber ofwhich member communicates with the said water-tight chamber, a ringsecured to a body part of the device and by is tightly clamped toa bodypart to make a Watertight joint, and an adjustable tuning ring bearingagainst said diaphragm inside of said first-named ring and outside ofsaid circular bridge. l A

2. A microphone instrument, for submarine use, comprising body casingparts within which is ai'chamber, one of said body parts having acircular projection affording a bridge over which said diaphragm isstretched, a 'diaphragm so mounted as to form one side of said chamberand render the same Water-tight, a microphone mount- /ed at one side ofsaid diaphragm in said chamber, a hollow collapsible member serving asan air container and the chamber ot Which communicates With the saidWater y tight chamber, a ring secured'to a body part of the device and bwhich ring said diaphragm is tightly c amped to a body part to ymake aWater-tight joint, an adjustable tuning ring bearing against saiddiaphragm inside of said first-namedl ring between said circular bridgeand the clamped edge of said diaphragm, and leads or conductorsextendingfrom said microphone to the outside of said casing partsthrough a Water-tight passage.

EDVARD C. WOOD.

